ADS 2362A is the prototype Algol
star, first discovered as variable by Montanari in 1669. The first period
determined by Goodricke in 1783, who also interpreted the variations as due
to eclipses. The prototype star proves to be a more a complicated system than
most of the Algol-type stars, i.e., compact triple system with separation of
the components well under 0.1". The components usually designated Algol
A, B, C, sometimes A, a, P. Two formerly additionally desig- nated components
D and E, inferred on the basis of an apparent 32 year apsidal motion, are now
considered spurious. The various Algol components must not be confused with the
visual components ADS 2362 B-E, optical companions at much greater distances
from A. ADS 2362A, EA 2.12 - 3.40V, 2.86732442d, abrupt period changes.
Orbital and rotation periods synchronized. Rotational velocity 65k/s. Radio
flares extending to about 1 A.U.,
not associated with X-ray activity. Radio flare activity appears correlated
with period discontinuities, attributed to "starquakes." Mass flow
from K to B8 component at rate of 1.8x10E-08 solar masses/year. Possible
circumstellar material associated with radio or H alpha emission.

Remarks: HD 193986, an object
with a V magnitude of 8.63 and an A0 spectral type, is a variable discovered by
the Hipparcos mission (ESA, 1997) after detecting light variations between 8m.64
and 8m.76. It could not be assigned a variable type and was
catalogued as an unsolved variable. HD 193986 is also a double star (ADS 13760
AB, Aitken, 1932) whose components, of magnitudes 9.7 and 9.9, are 0".3
apart.
The analysis of the Hipparcos satellite data indicated that this star might be
an Algol-type eclipsing binary star with a period of 1d.3955 or
double. To confirm the analysis results this star was observed for 27 nights,
between July 9, 2000 and November 9, 2000. Photometric observations showed that
HD 193986 is in fact an EA variable with a period of 2d.79. The star
fades 0m.10 at primary minimum and 0m.03 at the secondary
one. Since it could only be performed joint photometry of the optical binary
system, brightness variations must have a larger amplitude for the variable
component. The following ephemeris could also be computed:

Min I =
HJD 2451809.4772

+ 2d.791185

×E.

±0.0006

±0.000010

Acknowledgements: I am grateful to J. M.
Gomez-Forrellad for his analysis of the Hipparcos data, which allowed to solve
this variable.